/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.orc.nohive;

import org.apache.flink.core.fs.Path;
import org.apache.flink.orc.OrcColumnarRowSplitReader;
import org.apache.flink.orc.OrcFilters;
import org.apache.flink.orc.OrcSplitReader;
import org.apache.flink.orc.nohive.shim.OrcNoHiveShim;
import org.apache.flink.table.data.columnar.vector.ColumnVector;
import org.apache.flink.table.data.columnar.vector.VectorizedColumnBatch;
import org.apache.flink.table.types.DataType;
import org.apache.flink.table.types.logical.LogicalType;

import org.apache.hadoop.conf.Configuration;
import org.apache.orc.storage.ql.exec.vector.VectorizedRowBatch;

import java.io.IOException;
import java.util.List;
import java.util.Map;

import static org.apache.flink.orc.OrcSplitReaderUtil.convertToOrcTypeWithPart;
import static org.apache.flink.orc.OrcSplitReaderUtil.getNonPartNames;
import static org.apache.flink.orc.OrcSplitReaderUtil.getSelectedOrcFields;
import static org.apache.flink.orc.nohive.vector.AbstractOrcNoHiveVector.createFlinkVector;
import static org.apache.flink.orc.nohive.vector.AbstractOrcNoHiveVector.createFlinkVectorFromConstant;

/** Util for generating {@link OrcSplitReader}. */
public class OrcNoHiveSplitReaderUtil {

    /** Util for generating partitioned {@link OrcColumnarRowSplitReader}. */
    public static OrcColumnarRowSplitReader<VectorizedRowBatch> genPartColumnarRowReader(
            Configuration conf,
            String[] fullFieldNames,
            DataType[] fullFieldTypes,
            Map<String, Object> partitionSpec,
            int[] selectedFields,
            List<OrcFilters.Predicate> conjunctPredicates,
            int batchSize,
            Path path,
            long splitStart,
            long splitLength)
            throws IOException {

        List<String> nonPartNames = getNonPartNames(fullFieldNames, partitionSpec);

        int[] selectedOrcFields =
                getSelectedOrcFields(fullFieldNames, selectedFields, nonPartNames);

        OrcColumnarRowSplitReader.ColumnBatchGenerator<VectorizedRowBatch> gen =
                (VectorizedRowBatch rowBatch) -> {
                    // create and initialize the row batch
                    ColumnVector[] vectors = new ColumnVector[selectedFields.length];
                    for (int i = 0; i < vectors.length; i++) {
                        String name = fullFieldNames[selectedFields[i]];
                        LogicalType type = fullFieldTypes[selectedFields[i]].getLogicalType();
                        vectors[i] =
                                partitionSpec.containsKey(name)
                                        ? createFlinkVectorFromConstant(
                                                type, partitionSpec.get(name), batchSize)
                                        : createFlinkVector(
                                                rowBatch.cols[nonPartNames.indexOf(name)]);
                    }
                    return new VectorizedColumnBatch(vectors);
                };

        return new OrcColumnarRowSplitReader<>(
                new OrcNoHiveShim(),
                conf,
                convertToOrcTypeWithPart(fullFieldNames, fullFieldTypes, partitionSpec.keySet()),
                selectedOrcFields,
                gen,
                conjunctPredicates,
                batchSize,
                path,
                splitStart,
                splitLength);
    }
}
